Let's start with one of the best highlight videos on the internet:
The WR made so many big catches it takes a 10 minute video to show just the majority of them. Of course the biggest play has to be the X-Clown catch to beat the Rams divisional round in the 2003 march to the Super Bowl.
One thing these highlight videos always overlook about Smith is his blocking down field, whether its in support of another receiver with the ball or in the running game, he never stops. I'm sure you could fill up a highlight video with his key down field blocks.